This invention relates to a material for producing a lithographic printing plate comprising a thin glass support.
Lithographic printing is the process of printing from specially prepared surfaces, some areas of which are capable of accepting ink (oleophilic areas) whereas other areas will not accept ink (oleophobic areas). The oleophilic areas form the printing areas while the oleophobic areas form the background areas.
Two basic types of lithographic printing plates are known. According to a first type, so called wet printing plates, both water or an aqueous dampening liquid and ink are applied to the plate surface that contains hydrophilic and hydrophobic areas. The hydrophilic areas will be soaked with water or the dampening liquid and are thereby rendered oleophobic while the hydrophobic areas will accept the ink. A second type of lithographic printing plates operates without the use of a dampening liquid and are called driographic printing plates. This type of printing plates comprise highly ink repellant areas and oleophilic areas. Generally the highly ink repellant areas are formed by a silicon layer.
Common supports for use in lithographic printing plates are e.g. metal supports in particular grained and anodized aluminum or supports comprising a substrate such as e.g. paper or plastic film provided with a hydrophilic layer, preferably a hydrophilic layer that is cross-linked.
In lithographic printing plates it is important to use a support having high dimensional stability and high resistance against chemical influences. Glass is a support having very high dimensional stability and is highly unsensitive to chemical action. Therefore it would be a support of choice for lithographic printing plates if it were thin and flexible enough. Since different types of lithographic plate precursors, i.e. materials making it possible to produce a lithographic printing plates, are known in the art it is desirable to have a glass support that is useful for all types of lithographic printing plate precursors.
It is an object of the invention to provide a lithographic printing plate precursor having a support with high dimensional stability and good resistance to chemicals.
It is a further object of the invention to provide an alternative heat mode recording material for making a driographic printing plate of high quality and that preferably can be obtained without the need of solvent development or that can be obtained with ecologically more acceptable solvents and that comprises a support with high dimensional stability and good resistance to chemicals.
It is still a further object of the invention to provide a DTR (diffusion transfer) material, on a support with high dimensional stability and good resistance to chemicals for preparing a lithographic printing plate having good printing properties.
Further objects of the present invention will be clear from the description hereinafter.
The objects of the invention are realized by providing a material for making a lithographic printing plate comprising on a glass support a surface capable of being differentiated in ink accepting and ink repellant areas in accordance with an image pattern, characterized in that said glass support has a thickness of not more than 0.5 mm, a failure stress of at least 107 Pa and a Youngs modulus of not more than 1011 Pa.